Steering apparatus for soil-burrowing mole

ABSTRACT

This application discloses a steering scheme for an earthburrowing device. The scheme involves an articulatable tail with an active fin or fins. The fin stabilizes the device in steering situations where control would otherwise be lost, by permitting simultaneous steering and roll actions. In one embodiment, the fin protrudes a fixed distance into the soil stream but is pivoted perpendicular to the tail sleeve so that its angle of attack provides variable direction and speed of roll. In another, two retractable fins are used to impart respectively clockwise and counterclockwise rotation.

United States Patent [72] Inventors James C. Coyne New Providence;

Robert G. McCoy, Whippany, both of NJ. [21] App]. No. 883,786

[22] Filed Dec. 10, 1969 [45] Patented Dec. 28, 1971 [73] Assignee Bell Telephone Laboratories Incorporated Murray Hill, NJ.

[54] STEERING APPARATUS FOR SOIL-BURROWING MOLE 6 Claims, 6 Drawing Figs.

[52] U.S. Cl 175/73, 6l/72.7, 175/61, 299/30 [51] lnt.Cl E2lb 7/04 [50] Field of Search. 175/73, 74, 26, 94; 299/30; 61/72.?

[56] References Cited UNITED STATES PATENTS 1,276,706 8/1918 Aydelotte 175/19 X 3,326,008 6/1967 Baran et a1... 175/73 X 3,375,885 4/1968 Scott et alf. 175/26 3,480,092 11/1969 Reinold 175/19 3,465,834 9/1969 Southworth 61/72.? X

Primary ExaminerMarvin A. Champion Assistant Examiner-Richard E. F avreau Atl0rneysR. .l. Guenther and Edwin B. Cave ABSTRACT: This application discloses a steering scheme for an earth-burrowing device. The scheme involves an articulatable tail with an active fin or fins. The fin stabilizes the device in steering situations where control would otherwise be lost, by permitting simultaneous steering and roll actions. In one embodiment, the tin protrudes a fixed distance into the soil stream but is pivoted perpendicular to the tail sleeve so that its angle of attack provides variable direction and speed of roll. In another, two retractablefins are used to impart respectively clockwise and counterclockwise rotation.

PATENTEnniczaasn SHEET 1 OF 3 FIG.

PRIOR ART J. c. cor/v5 'R-G. Mc car 66% f. QM

ATTOPNE V FIELD OF THE INVENTION This invention relates to underground burrowing devices or moles; and in particular to their steering apparatus.

BACKGROUND OF THE INVENTION In the copending application of J. C. Coyne, Ser. No. 792,893, filed Dec. 27, 1968, there is incidentally disclosed a molesteering scheme consisting of a tail section pivotable about a clevis pin which in turn is mounted on the mole body in a powered rotatable assembly. By suitable manipulation of these components, the tail can be made to assume any desired angular attitude with respect to the mole body.

While affording generallysatisfactory steering, the above apparatus in some burrowing situations has been found deficient. One such case, termed slip-back," arises when the mole is undergoing a change in the plane of a curved trajectory, or a corkscrew turn. The routine calls for the tail to be first straightened, then rotated and finally articulated at the new rotational angle. The tendency on rearticulation, however, is for the mole to roll back into the existing tunnel of the old trajectory rather than strike a new gripping surface into the tunnel wall. So until the mole is driven into virgin soil along a fairly straight trajectory, the new path may not be achieved.

Another deficiency of the earlier steering is its inability to readily counteract the forces which tend to make the mole rise to the surface. Specifically, when the tail is articulated these forces acting on the tail tend to make it rise, in turn causing the tail-body plane to seek the vertical. The resultant change of trajectory is most pronounced if the original trajectory plane is horizontal.

A further drawback to the earlier steering construction is that the tail could not be rotated while articulated, due to the undesirability of increasing the mole body length sufiiciently to provide for an adequate roll torque motor. It accordingly was necessary to advance the mole enough to enable the tail to be straightened, and then perform the tail rotation. The added mole travel required for this operation creates a transportation lag that lessens the ability to steer a desired trajectory, especially since the number of such operations necessary in a given run is unpredictable. 7

Another problem, one of major practical import, is that the powered rotating joint detracted from overall mole performance because of its size and weight.

Accordingly, the following are the inventions major objects:

to provide a mole steering more realizable in practice;

to achieve finer and more continuous control over mole steering;

to more effectively and continuously counteract the tendency of the mole to surface;

to reduce the transportation lags;

to avoid the problem of mole slip-back when it is attempted to roll to a new steering plane;

to provide greater rolling'torques; and

to reduce the length, weight and complexity of a mole.

SUMMARY OF THE INVENTION In accordance with the invention, a fin is mounted outside the tail skin on a shaft, with the majority of the fin surface aft of the pivot point. In a particular embodiment the fin is permanently outside and the shaft is rotatable so as to tilt the fin. At any articulation angle, the'fin is in contact with soil. Roll control is achieved bytilting the fin which then, rudderlike, responds to the moles further forward movement by twisting the tail and mole substantially around the latters axis until a desired new tail orientation is readied.

Advantageously, if anew trajectory plane is being sought, it is not necessary to straighten the tail. Rather, with the fin actuated, the tail may be left articulated; and, as the mole approachesthe new plane, the fin angle is eased.

Importantly, the fin tilt develops torques about the mole centerline well in excess of that needed to effect rotation of the tail and mole body. It accordingly is possible to eliminate all mechanisms relating to the earlier power rotation of the tail section, with an attendant saving of critical space. It can be seen that the power required to tilt the fin is small compared to that required by powered rotation, since in the instant case, the power required for rolling the mole is derived from the main propulsion source.

In a second embodiment, the fin comprises a right and a left member, each fully retractable into the tail with the tail skin as a bearing surface, the members are supported at opposing fixed angles with respect to the tail's axis. The right member when extended reacts to soil pressures by causing clockwise rotation of the tail; similarly, the left member when extended causes counterclockwise tail rotation.

The invention and its further objects, features and advantages will be more fully appreciated with a reading of the following detailed description of an illustrative embodiment.

THE DRAWING FIG. I is a schematic side perspective of prior art mole steering;

FIG. 2 is a schematic side perspective view of one embodiment of the instant invention;

FIG. 3 is a side perspective view of the mole tail;

FIG. 4 is an end perspective view of a second inventive embodiment;

FIG. 5 is a side perspective view of a second, embodiment; and

ment.

ILLUSTRATIVE EMBODIMENTS A typical prior art mole steering scheme is shown in FIG. I. There, the mole, designated 10, consists of a body 11, a tail l2 and power connections 13 leading to electrical and hydraulic sources (not shown). Tail I2 is supported ona clevis joint 14 which includes a two-part clevis pin 15. The body side of joint 14 is rotatably mounted on bearing surface 16 of body 11. Steering is effected by flexing the clevis joint 14, by means not shown, in combination with a suitable power rotation of tail 12 on bearing surface 16, also by means not'shown.

One embodiment of the present invention, depicted in FIG. 2, is a mole 10a comprising most of the basic elements of FIG. 1 including body 11, tail I2, power connections 13, clevis joint 14, and clevis pin 15. Additionally, mole 10a comprises fin 17. Joint 14 is, in the FIG. 2 embodiment, not rotatably mounted with respect to body II. In such case, the tail I2, as it rolls in response to fin forces, causes rotation of the entire mole. Alternatively, however, thebearing surface 16 depicted in FIG. l is readily incorporated if desired in the FIG. 2 inventive embodiment albeit at the cost of added mole length.

FIG. 3 portrays in more detail the interior of the tail 12 shown in FIG. 2. A depressed flat I8 in the after exterior surface of tail l2affords a bed for fin 17. A mounting pin 19 and integral hub 20 are rigidly connected to fin I7. Hub 20 contacts the flat I8, and the undersurface 24 of fin I7 clears fiat 18 by about 5 mils, which serves to reduce the torque required to rotate fin 17 in the presence of dirt. The pin extends perpendicularly through the tail skin at flat I8; and is perpendicular also to clevis pin 15.

Fin 17 is mounted slightly offcenter in a fore-aft sense, with respect to pin l9'enough to place the majority of fin surface aft of the pin. This expedient causes the fin l7, absent a turning torque applied through pin 19, to passively seek alignment with the direction of mole travel, thus obviating need for positive nonnalizing gear.

Advantageously, fin I7 is shaped with a forward bevel 21, an after bevel 22, useful for backing in the tunnel, and a streamlined flat top 23. The forward wall 25 of flat 18 is struck with a radius that places it just beyond the path of travel of the FIG. 6 is a schematic perspective view of a second embodiforward fin tip 26. The latter can include a short vertical section, as shown in FIG. 3.

The fin 17 is actuated by the exemplary apparatus depicted in FIG. 3. Two hydraulic cylinders 30, 31 are rigidly mounted in the rear interior of tail 12 and are hydraulically connected to a source (not shown) through hoses 32, 33. Pistons 34, 35 are respectively actuated through cylinders 30, 31 and contact the separate ends 36, 37 of a two-arm crank 27 rigidly connected to the pin 19. Positive fin movement away from normal to all angles up to 3035 in either direction thus is afforded. Return of the fin 17 to normal fore-aft orientation is passively realized in the embodiment shown. For faster action the pistons can be alternately actuated. A further alternative is a single double-acting piston connected through a scotch yoke to one of the crank arms, the specifics of which are readily visualized by reference to FIG. 3.

Pivoting of tail 12 can be achieved in any of numerous fashions. In one such scheme shown in FIG. 3, tail l2 pivots about clevis pin by virtue of a push rod 40 mounted eccentrically in the tail and acting on a hemispheric ball 41. The latter is suitably bushed in a ball joint mounted on mole body 11. Rod 40 is actuated by an annular piston 42. Piston 42 moves in hydraulic cylinder 43 which is also annular. Power connections 13 are conveniently led through the annulus of piston 42 and on forward to the mole body.

In an alternate inventive embodiment shown in FIGS. 4-6, the tail is mounted as in FIG. 2, and two fins 50, 51 are used: a right member 50 and a left member 51. The members 50, 51 are separately retractable through skim slots 52, 53 from a withdrawn position wherein the leading edge of each member is substantially flush with the tail surface adjacent the slot, to an extended position beyond the tail skin. Support for the sections 50, 51 include two mounting blocks 54, 55 fastened to the interior skin of tail 12. Each block comprises a pin 56, 57 to which the respective members 50, 51 are pivotally mounted. Piston rods 58, 59 are connected between offset shoulders 60, 61 of the members 50, 51 and hydraulic cylinders 62, 63. The latter are separately actuated through hydraulic lines 64, 65 from a source not shown.

By extending the appropriate one of members 50, 51, a rotating force in the desired direction is applied to the tail as a result of the action of the soil on the fin. Advantageously, lesser frictional penetration forces are encountered when the fins can be retracted. Further, smaller actuation forces are required since in the instant embodiment, the members 50, 51 are driven edgcwise into the soil.

In constructing the FIG. 4-6 embodiment, observance of certain geometric relationships is advantageous. The plane of motion of either of the members 50, 51 if viewed edge-on, intersects the mole longitudinal axis at an angle of about 30. The angle of intersection of the respective planes of motion is in the range of to The line of intersection of the two planes is in a plane that is normal to the axis of clevis pin 15 and that contains the tail axis. This line is inclined by about 30 with respect to the tail longitudinal axis.

The spirit of the invention is embraced in the claims to follow.

What is claimed is: 1. For a soil-burrowing mole having a main missilelike body, steering apparatus comprising:

a tail comprising a flattened exterior rear surface, means for articulating said tail about an axis on the after part of said body, a pivot pin extending from the tail interior perpendicularly through said surface, an elongated fin rigidly mounted on said pin with a majority of the fins surface area aft of said pin, and means for rotating said pin thereby to vary the reactive forces impinging on said fin from soil contact. 2. Apparatus in accordance with claim 1, wherein said rotating means comprises a crank connected to the interior end of said pivot pin and having at least one arm, and a hydraulic pistonfor driving each said arm.

3. Apparatus in accordance with claim 1, wherein said rear surface is a flat depression having a forward wall formed to a radius slightly in excess of the circular path described by the forward end of said fin.

4. Apparatus in accordance with claim 3, wherein the extreme bottom portions of said fin are in close proximity to said flat depression.

5. For a soil-burrowing mole having a main missilelike body, steering apparatus comprising:

a tail comprising a skin slot,

a clevis pin mounted in perpendicular relation to the iongitudinal axis of said body,

means for articulating said tail about said clevis pin a fin pivoted from the interior of said tail for travel through said slot, and

means for effecting the pivoting of said fin from a position in which the leading edge is substantially flush with the tail surface adjacent said slot, to any one of plural extended positions offering varying amounts of fin surface area for impingement with soil.

6. Apparatus in accordance with claim 5, wherein the number of said fins comprises two; and in which the angle of intersection of the respective planes of motion of said two fins is in the range 90 to 150, with the line of intersection of said two planes being in a plane that is substantially normal to the axis of said clevis pin and that contains the tail axis, said line of intersection being inclined to said tail longitudinal axis by about 30. 

1. For a soil-burrowing mole having a main missilelike body, steering apparatus comprising: a tail comprising a flattened exterior rear surface, means for articulating said tail about an axis on the after part of said body, a pivot pin extending from the tail interior perpendicularly through said surface, an elongated fin rigidly mounted on said pin with a majority of the fin''s surface area aft of said pin, and means for rotating said pin thereby to vary the reactive forces impinging on said fin from soil contact.
 2. Apparatus in accordance with claim 1, wherein said rotating means comprises a crank connected to the interior end of said pivot pin and having at least one arm, and a hydraulic piston for driving each said arm.
 3. Apparatus in accordance with claim 1, wherein said rear surface is a flat depression having a forward wall formed to a radius slightly in excess of the circular path described by the forward end of said fin.
 4. Apparatus in accordance with claim 3, wherein the extreme bottom portions of said fin are in close proximity to said flat depression.
 5. For a soil-burrowing mole having a main missilelike body, steering apparatus comprising: a tail comprising a skin slot, a clevis pin mounted in perpendicular relation to the longitudinal axis of said body, means for articulating said tail about said clevis pin a fin pivoted from the interior of said tail for travel through said slot, and means for effecting the pivoting of said fin from a position in which the leading edge is substantially flush with the tail surface adjacent said slot, to any one of plural extended positions offering varying amounts of fin surface area for impingement with soil.
 6. Apparatus in accordance with claim 5, wherein the number of said fins comprises two; and in which the angle of intersection of the respective planes of motion of said two fins is in the range 90* to 150* , with the line of intersection of said two planes being in a plane that is substantially normal to the axis of said clevis pin and that contains the tail axis, said line of intersection being inclined to said tail longitudinal axis by about 30* . 